Connected: An Internet Encyclopedia
Review

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Up: Programmed Instruction Course
Up: Section 1

### Review

Congratulations! You've completed the first section of the Programmed Instruction Course. Let's summarize the topics covered in this section:

- Protocol

  - A protocol is "a formal description of message formats and the rules two or more machines must follow to exchange those messages."
  - Protocols let us perform operations on other computers over a network.
  - Many protocols can be in use at once.
  - Protocols should be as specific to one task as possible.

- Standard

  - Standards are protocols that everyone has agreed upon.
  - Standard organizations exist to develop, discuss and enhance protocols.
  - The most important Internet standard organization is the Internet Engineering Task Force (IETF).
  - The most important Internet standard documents are the Requests For Comments (RFCs).

- Protocol Layering

  - Protocols are usually organized by layering them atop one another.
  - Protocol layers should have specific, well-defined functions.
  - The most important protocol layering designs are the 4-layer Department of Defense (DoD) Model, and the 7-layer Open System Interconnect (OSI) Model.

- 4-Layer DoD Model

  - The 4-layer DoD layered protocol model consists of the Process, Host-to-Host, Internet, and Network Access Layers.
  - The DoD Model was developed for the Internet.
  - The core Internet protocols adhere to the DoD Model.

- Encapsulation

  - Encapsulation happens when one protocol's message is embedded into another protocol's message.
  - Protocol layering is implemented through encapsulation.

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Now, click here to proceed into Section 2.

Connected: An Internet Encyclopedia
Review